I have an RV with a generator and instead of buying one, I'd like to use the RV as my emergency power source. My thought is that I could install a disconnect at the main panel feed, and then feed power from the generator through the sub panel back to the house.

My outbuilding has a 100 amp sub panel that is fed with a dual pole 100 amp circuit breaker from the main panel in the house. It looks like there are three wires feeding the sub panel, two hots and a ground. i didn't see a neutral bus, only a common ground bar that both grounds and neutrals are wired to for all of the existing circuits. One of the existing outlets is a special one that is fed back to what I believe is a 240 volt 40 amp dual pole breaker, which is why I don't think there is a neutral ran to the sub panel. It is for a air compressor. I have a 30 amp 120 V RV outlet already.

This house and out building were built in 2004.

So, ignoring for a minute that the sub panel should have separate neutral and ground buses,  would this work?

Copy and paste this in Mikeholts.com /forum

Your Just Plain Mean for.that.

Not sure I follow. That site is parked.

It is or was an electrician's forum.



Do it right, do it safe, interlock your service disconnect with the generator feed
It is not hard.
It is not expensive.
It may be just a little inconvenient because you might not be able to do this in your shop subpanel.
If that's the case, buy or make an extension cord (figure voltage drop and size conductors accordingly) or park the RV next to the house when needed for backup power.

Lots of threads with lots of pictures on this site for generator interlock installations.

First:  ac works both directions.  The transformer down the street lets say takes 7,200volts and brings it down to two legs of 120 volts AC.  When the power goes out and you back feed the house and forget to disconnect the main (could be at the main panel or the meter) then your backfeed that transformer and 7,200 volts is sent down the line to kill the lineworkers.

B.   If you backfeed a 240 outlet it will power both sides of the panel.  If you backfeed a 120v outlet it will power the side that the breaker is for that outlet.

III.     It can be safely done, but most likely breaks the law because of the danger it poses to lineworkers.

All breakers should be stripped (off/open) before an illegal activity like this is started.  Lock out tag out the main.

I got it. I know that AC works both ways. Hence, the disconnect. Had a friend who is also an electrician tell me that while it would work, it was a bad idea, that I could open up myself to potential problems, and that it wasn't to code, so I will take a different approach.

Does the subpanel have the neutral and ground bonded together?
That's a code violation.  (I see your final comment).
They should be bonded in the main panel, but you should have separate neutral and ground buses in a sub panel.
The outbuildings sub panel needs its own grounding rods too.

After that, installing an interlock with a back feed breaker is relatively simple.
You'll need to install it in the main panel.
If you install it in the sub panel, you'll only power the sub panel loads when you throw the interlock because you have to shut off the main breaker to the panel in order to throw the interlock.

Op I am looking at doing the same thing so I will just ride along for the learning

This is what you seek.

http://www.interlockkit.com/